While there may be a general desire to minimize the size of mobile telephones, there is a physical restriction in reducing the size due to a need for the ear piece to be positioned proximate the user's ear at the same time as the mouth piece is positioned proximate the user's mouth. This theoretically dictates that the length of the mobile telephone must be a certain minimum size.
It has been recognized that the position of the ear piece and the mouth piece is only critical when the mobile telephone is in use. Based on this, mobile telephones have been developed with a ‘flip-cover.’ When the mobile telephone is not in use, the flip-cover folds or slides back onto a keypad housing of the mobile telephone and, therefore, does not increase the overall size of the mobile telephone. When a call is to be made or received, the flip-cover is opened such that the length of the mobile telephone becomes longer and the mouthpiece for the user is more practically positioned.
Typically, mobile telephone designs having a flip-cover include a means such that the state of the flip-cover, either open or closed, is detected. The detection of the flip-cover state, for example, may be used for answering a call (on opening the flip-cover) and terminating a call (on closing the flip-cover).
Presently, a sensor switch, such as a micro-switch, may be recessed within the surface of the keypad housing to engage with a switch activator on the cover. The switch activator is usually a small protrusion that extends into a recess of a surface of the mobile telephone when the flip-cover is closed thereby engaging, or activating, the sensor switch. This sensor switch provides an input signal to a general-purpose input/output (GPIO) pin of a micro-controller within the mobile telephone. Thus, the micro-controller within the mobile telephone receives a dedicated signal indicating whether the flip-cover is open or closed.
One disadvantage with this present detection of the flip-cover state is that the provision of extra pins on the micro-controller integrated circuit package increases the cost of the integrated circuit. Therefore, the provision of a dedicated GPIO pin to the micro-controller for the purpose of detecting the status of the flip-cover increases the cost of the micro-controller integrated circuit. Alternatively, using a spare GPIO pin for this purpose prevents it from being used for another purpose.
One proposal for detecting the flip-cover state includes using a switch matrix associated with a keypad of the mobile telephone. A switch of the switch matrix may receive a signal which in an alternate detection process would have been provided to the GPIO pin of the micro-controller. In such a proposal, when the particular switch of the matrix is not pressed, a signal is sent to a keypad controller to indicate that the flip cover is open. The disadvantage with this proposal, however, is that an entire row of the keypad switch matrix is inoperable while the flip cover is open since one of the switches in that row of the switch matrix will be constantly activated. Hence that row is not usable. The proposal, therefore, is not practical since it is unlikely that an entire row of the switch matrix may be unused and still provide a sufficient number of keys for normal operation of the mobile telephone.
Accordingly, what is needed in the art is an improved arrangement for detecting the status of a flip-cover associated with a keypad apparatus, such as a mobile phone, that overcomes the deficiencies in the prior art.